ISL78692EVAL1Z [RENESAS]
Li-ion/Li-Polymer Battery Charger;
| 型号： | ISL78692EVAL1Z |
| 厂家： | 
RENESAS TECHNOLOGY CORP |
| 描述： | Li-ion/Li-Polymer Battery Charger 电池 |
| 文件： | 总18页 (文件大小：990K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
DATASHEET
ISL78692
Li-ion/Li-Polymer Battery Charger
FN8692
Rev.1.00
Mar 29, 2017
The ISL78692 is an integrated single-cell Li-ion or Li-polymer
battery charger capable of operating with an input voltage
as low as 2.65V (cold crank case). This charger is designed to
work with various types of AC adapters or a USB port.
Features
• Complete charger for single-cell Lithium chemistry batteries
• Integrated power transistor and current sensor
• Reverse battery leakage 700nA
The ISL78692 operates as a linear charger when the AC
adapter is a voltage source. The battery is charged in a CC/CV
(constant current/constant voltage) profile. The charge current
is programmable with an external resistor up to 1A. The
ISL78692 can also work with a current-limited adapter to
minimize the thermal dissipation.
• 1% initial voltage accuracy
• Programmable CC current up to 1A
• Charge current thermal foldback
• NTC thermistor interface for battery temperature alert
• Accepts CV and CC types of adapters or USB bus power
• Preconditioning trickle charge
The ISL78692 features charge current thermal foldback to
guarantee safe operation when the printed circuit board’s
thermal dissipation is limited due to space constraints.
Additional features include preconditioning of an
over-discharged battery, an NTC thermistor interface for
charging the battery in a safe temperature range and
automatic recharge. The device is specified for operation in
ambient temperatures from -40°C to +85°C and is offered in
a 3x3mm thermally enhanced DFN package.
• Guaranteed to operate down to 2.65V after start-up
• Ambient temperature range: -40°C to +85°C
• AEC-Q100 qualified
Applications
• Automotive systems
• eCall systems
Related Literature
• Technical Brief TB363 “Guidelines for Handling and
Processing Moisture Sensitive Surface Mount Devices
(SMDs)”
• Backup battery systems
• Technical Brief TB379 “Thermal Characterization of
Packaged Semiconductor Devices”
• UG001, “ISL78692EVAL1Z Evaluation Board User Guide”
CONSTANT
CURRENT
MODE
CONSTANT
VOLTAGE
MODE
TRICKLE
MODE
INHIBIT
VIN
BATTERY
PACK
ISL78692
INPUT VOLTAGE
VCH
5V
VIN
V
BAT
BATTERY VOLTAGE
R
1
C
C1
10µF
2
R
100k
1
100k
+
-
TEMP
2x10µF
FAULT
STATUS
EN
R
1k
1
VTRICKLE
V2P8
IREF
R
160k
1
EN
ICHARGE
C3
TIME
GND
1µF
CTIME
15nF
CHARGE CURRENT
I
CHARGE/10
TIMEOUT
FIGURE 1. TYPICAL APPLICATION
FIGURE 2. TYPICAL CHARGE CURVES USING A CONSTANT
VOLTAGE ADAPTER
FN8692 Rev.1.00
Mar 29, 2017
Page 1 of 18
ISL78692
Block Diagram
QMAIN
VIN
VBAT
C1
REFERENCES
V2P8
TEMPERATURE
MONITORING
QSEN
100000:1
CURRENT
MIRROR
IT
VIN
VBAT
ISEN
INPUT_OK
+
-
VPOR
+
-
IREF
+
-
+
IR
100mV
RIREF
CURRENT
CHRG
REFERENCES
+
-
IMIN
VCH
+
-
VMIN
TRICKLE/FAST
MINBAT
ISEN
+
-
VRECHRG
MIN_I
+
-
V2P8
RECHARGE
UNDER-
TEMPERATURE
STATUS
FAULT
LOGIC
STATUS
OVER-
TEMPERATURE
NTC
TEMP
INTERFACE
BATT REMOVAL
FAULT
V2P8
OSC
COUNTER
TIME
GND
INPUT_OK
EN
TABLE 1. KEY DIFFERENCES BETWEEN FAMILY OF PARTS
OUTPUT
VOLTAGE (V)
RECHARGE
THRESHOLD (V)
TRICKLE CHARGE
THRESHOLD (V)
PART NUMBER
ISL78692
4.1
3.9
2.8
2.6
ISL78693
3.65
3.25
FN8692 Rev.1.00
Mar 29, 2017
Page 2 of 18
J2
JP2
VBAT
UNNAMED_1_SMLED_I292_B
OUTPUT
1
2
3
TP3
TP4
1
2
D2
UNNAMED_1_AMP6448033
C7
OPEN
C2
3
VIN
GND2
UNNAMED_1_SMLED_I291_B
TP1
TP2
D1
C1
GND1
10UF
1UF
J1
R4
1
U1
1
2
UNNAMED_1_AMP6448032_I352_IN2
TP9
2
DNP
1
2
10
9
VIN
VBAT
TP10
FAULT
STATUS
TEMP
FAULT
STATUS
TIME
TEMP
IREF
V2P8
EN
IREF
V2P8
2
3
8
JP1
TIME
4
7
1
2
3
TP5
TP6
JP4
EN
5
6
TP8
GND
11
EPAD
UNNAMED_1_AMP2923041_I351_IN1
ISL78692-1CR3Z
TP7
2
3
1
4
J3
SW1
UNNAMED_1_SDA08HX_I326_PIUNN16NAMED_1_SDUAN0N8AHMXE_ID3_216_SPDINA1048HX_I326_PIUNN13NAMED_1_SDUAN0N8AHMXE_ID3_216_SPDIUNAN101N8AHMXE_ID3_216_SPDINA1008HX_I326_PIN9
1
2
TIME
EN
3
4
5
6
7
8
500MA
400MA
NA
TEMP
TEMP
TEMP
JP4
1,2 USB 500MA
2,3 USB 100MA
FIGURE 3. ISL78692EVAL1Z SCHEMATIC
ISL78692
Pin Configuration
ISL78692
(10 LD 3x3 DFN)
TOP VIEW
VIN
1
10 VBAT
FAULT
STATUS
TIME
2
3
4
5
9
8
7
6
TEMP
IREF
V2P8
EN
GND
Pin Descriptions
PIN #
PIN NAME
DESCRIPTION
1
2
VIN
VIN is the input power source.
FAULT
FAULT is an open-drain output indicating fault status. This pin is pulled to LOW under any fault
conditions.
3
4
STATUS
TIME
STATUS is an open-drain output indicating charging and inhibit states. The STATUS pin is pulled LOW
when the charger is charging a battery.
The TIME pin determines the oscillation period by connecting a timing capacitor between this pin and
GND. The oscillator also provides a time reference for the charger.
5
6
GND
EN
GND is the connection to system ground.
EN is the enable logic input. Connect the EN pin to LOW to disable the charger or leave it floating to
enable the charger.
7
V2P8
The V2P8 is a 2.8V reference voltage output. The 2.8V is present when VIN is above 3.4V typical. If VIN
falls below 2.4V typical the V2P8 output will be at 0V.
8
9
IREF
This is the programming input for the constant charging current.
TEMP
TEMP is the input for an external NTC thermistor. The TEMP pin is also used for battery removal
detection.
10
VBAT
EPAD
VBAT is the connection to the battery.
The metal slug on the bottom surface of the package is floating. Tie to system GND.
Ordering Information
PART NUMBER
(Notes 1, 2, 3)
PART
MARKING
TEMP RANGE
(°C)
PACKAGE
(Pb-Free)
PKG
DWG
ISL78692-1CR3Z
ISL78692EVAL1Z
NOTE:
8692
-40 to +85
10 Ld 3x3 DFN
L10.3x3
Evaluation Board for the 3x3 DFN Package Part
1. Add “-T” suffix for 6k unit or “-T7A” suffix for 250 unit tape and reel options. Refer to TB347 for details on reel specifications.
2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte
tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil
Pb-free products are MSL These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach
materials, and 100% matte tin plate plus classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC
J STD-020.
3. For Moisture Sensitivity Level (MSL), please see device information page for ISL78692. For more information on MSL, see Technical Brief TB363.
FN8692 Rev.1.00
Mar 29, 2017
Page 4 of 18
ISL78692
Absolute Maximum Ratings
Thermal Information
Supply Voltage (VIN). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-0.3V to 7.0V
Output Pin Voltage (VBAT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-0.3V to 5.5V
Output Pin Voltage (V2P8). . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-0.3V to 3.2V
Signal Input Voltage (EN, TIME, IREF, TEMP). . . . . . . . . . . . . . .-0.3V to 3.2V
Output Pin Voltage (STATUS, FAULT). . . . . . . . . . . . . . . . . . . . . .-0.3V to 7.0V
Charge Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6A
ESD Rating:
Human Body Model (Tested per AEC-Q100-002). . . . . . . . . . . . . . . . . . 4kV
Charge Device Model (Tested per AEC-Q100-011) . . . . . . . . . . . . . 1.25kV
Latch-up (Per JESD78D; Class 2, Level A, AEC-Q100-004) . . . . . . . . 100mA
Thermal Resistance (Typical)
3x3 DFN Package (Notes 4, 5) . . . . . . . . . .
Maximum Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . +150°C
Maximum Storage Temperature Range . . . . . . . . . . . . . .-65°C to +150°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see TB493
(°C/W)
46
(°C/W)
4
JA
JC
Recommended Operating Conditions
Ambient Temperature Range . . . . . . . . . . . . . . . . . . . . . . . .-40°C to +85°C
Supply Voltage, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..4.3V to 5.5V
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product
reliability and result in failures not covered by warranty.
NOTES:
4. is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See Tech
JA
Brief TB379.
5. , “case temperature” location is at the center of the exposed metal pad on the package underside. See Tech Brief TB379.
JC
Electrical Specifications Typical values are tested at V = 5V and at an Ambient Temperature of +25°C. Unless otherwise noted.
IN
Boldface limits apply across the operating temperature range, -40°C to +85°C and V range of 4.3V to 5.5V (see Note 6).
IN
MIN
MAX
PARAMETER
POWER-ON RESET
Rising V Threshold
SYMBOL
TEST CONDITIONS
(Note 6)
TYP
(Note 6)
UNITS
3.0
3.4
2.4
4.0
V
V
IN
Falling V Threshold
IN
2.11
2.65
STANDBY CURRENT
VBAT Pin Leakage
I
V
V
V
= 5.5V, V = 0V, EN = 0.8V
IN
0.7
30
1
3.0
µA
µA
VBLKG
BAT
BAT
BAT
VIN Pin Standby Current
VIN Pin Quiescent Current
VOLTAGE REGULATION
I
OPEN, V = 5.0V, EN = 0.8V
IN
200
INSBY
I
OPEN, V = 5.5V, EN FLOAT
IN
mA
Q
Output Voltage
V
V
V
OPEN
4.015
4.10
270
4.185
450
V
CH
BAT
BAT
Dropout Voltage
V
= 3.7V, I = 500mA
IN
mV
DO
CHARGE CURRENT
Constant Charge Current (Note 8)
Trickle Charge Current
I
I
I
I
I
I
R
R
= 160kΩ, V
= 160kΩ, V
= 3.7V
= 2.4V
430
390
65
500
55
570
540
104
100
4.05
3.0
mA
mA
mA
mA
mA
mA
mA
CHARGE
TRICKLE
CHARGE
TRICKLE
CHARGE
TRICKLE
IREF
IREF
BAT
BAT
Constant Charge Current (Note 8)
Trickle Charge Current
IREF pin voltage > 1.2V, V
IREF pin voltage > 1.2V, V
IREF pin voltage < 0.4V, V
IREF pin voltage < 0.4V, V
= 3.7V
= 2.4V
= 3.7V
= 2.4V
450
45
BAT
BAT
BAT
BAT
Constant Charge Current (Note 8)
Trickle Charge Current
80
10
End-of-Charge Current
I
35
60
EOC
RECHARGE THRESHOLD
Recharge Voltage Falling Threshold
TRICKLE CHARGE THRESHOLD
Trickle Charge Threshold Voltage
V
V
3.7
2.7
3.9
2.8
V
V
RECHRG
TRICKLE
FN8692 Rev.1.00
Mar 29, 2017
Page 5 of 18
ISL78692
Electrical Specifications Typical values are tested at V = 5V and at an Ambient Temperature of +25°C. Unless otherwise noted.
IN
Boldface limits apply across the operating temperature range, -40°C to +85°C and V range of 4.3V to 5.5V (see Note 6).
IN
MIN
MAX
PARAMETER
TEMPERATURE MONITORING
Low Temperature Threshold
High Temperature Threshold
Battery Removal Threshold (Note 7)
Charge Current Foldback Threshold
Current Foldback Gain (Note 7)
OSCILLATOR
SYMBOL
TEST CONDITIONS
(Note 6)
TYP
(Note 6)
UNITS
V
V2P8 = 3.0V
V2P8 = 3.0V
1.45
0.36
2.1
1.51
0.38
2.25
100
100
1.57
0.4
V
TMIN
V
V
V
TMAX
V
V2P8 = 3.0V, Voltage on temperature
Junction temperature
3.0
RMV
T
85
125
°C
FOLD
G
mA/°C
FOLD
Oscillation Period
t
C
= 15nF
2.2
3.0
3.6
0.8
0.4
ms
OSC
TIME
LOGIC INPUT AND OUTPUT
EN Input Low
V
V
IREF Input High
1.2
5
IREF Input Low
V
STATUS/ FAULT Sink Current
Pin voltage = 0.8V
11
mA
NOTES:
6. The Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by
characterization and are not production tested.
7. This parameter is not tested in production.
8. Measured using pulse load.
FN8692 Rev.1.00
Mar 29, 2017
Page 6 of 18
ISL78692
Typical Operating Performance The test conditions for the Typical Operating Performance are: V = 5V,
IN
T
= +25°C, R
= 160kΩ, V = 3.7V, Unless Otherwise Noted.
BAT
A
IREF
4.150
4.140
4.130
4.120
4.110
4.100
4.090
4.080
4.070
4.060
4.050
4.150
4.140
4.130
4.120
4.110
4.100
4.090
4.080
4.070
4.060
4.050
-40°C
-40°C
+85°C
+25°C
+25°C
+85°C
0
100
200
300
(mA)
400
500
4.0
4.5
5.0
5.5
6.0
6.5
I
V
(V)
BAT
IN
FIGURE 4. VOLTAGE REGULATION vs CHARGE CURRENT
FIGURE 5. NO LOAD VOLTAGE vs TEMPERATURE
0.55
0.55
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
+25°C
0.50
0.45
+25°C
-40°C
0.40
0.35
0.30
0.25
0.20
0.15
0.10
+85°C
-40°C
+85°C
2.9
3.1
3.3
3.5
3.7
(V)
3.9
4.1
4.3
2.9
3.1
3.3
3.5
3.7
(V)
3.9
4.1
4.3
V
V
BAT
BAT
FIGURE 6. CHARGE CURRENT vs OUTPUT VOLTAGE, R
= 158k
FIGURE 7. CHARGE CURRENT vs OUTPUT VOLTAGE, R
= 200k
IREF
IREF
0.6
0.45
0.40
0.35
V
= 4.05V
BAT
0.5
0.4
0.3
0.2
0.1
0.0
V
= 4.05V
BAT
V
= 3.7V
BAT
0.30
0.25
0.20
0.15
0.10
0.05
0.00
V
= 3.7V
BAT
V
= 2.9V
BAT
V
= 2.9V
BAT
-40
-20
0.0
20
40
60
80
100
120
-40
-20
0
20
40
60
80
100
120
JUNCTION TEMP (°C)
JUNCTION TEMP (°C)
FIGURE 8. CHARGE CURRENT vs JUNCTION TEMPERATURE,
= 158k
FIGURE 9. CHARGE CURRENT vs JUNCTION TEMPERATURE,
= 200k
R
R
IREF
IREF
FN8692 Rev.1.00
Mar 29, 2017
Page 7 of 18
ISL78692
Typical Operating Performance The test conditions for the Typical Operating Performance are: V = 5V,
IN
T
= +25°C, R
= 160kΩ, V
= 3.7V, Unless Otherwise Noted. (Continued)
BAT
A
IREF
0.6
0.6
0.5
0.4
0.3
0.2
0.1
0.5
0.4
0.3
0.2
0.1
+25°C
+25°C
+85°C
+85°C
4.3
4.5
4.7
4.9
(V)
5.1
5.3
5.5
4.3
4.5
4.7
4.9
(V)
5.1
5.3
5.5
V
V
IN
IN
FIGURE 11. CHARGE CURRENT vs INPUT VOLTAGE, V
= 3V,
FIGURE 10. CHARGE CURRENT vs INPUT VOLTAGE, V
= 3V,
BAT
BAT
R
= 200k
R
= 158k
IREF
IREF
2.95
2.90
2.85
2.80
2.75
2.900
2.875
2.850
2.825
2.800
+85°C
+25°C
-40°C
+85°C
+25°C
-40°C
0
2
4
6
8
10
12
3.0
4.0
5.0
(V)
6.0
7.0
V
I2P8 LOAD CURRENT (mA)
IN
FIGURE 12. V2P8 OUTPUT vs INPUT VOLTAGE AT NO LOAD
FIGURE 13. V2P8 OUTPUT vs LOAD CURRENT
28
35
30
25
20
15
10
V
= 5.5V
IN
27
26
25
24
23
22
+25°C
-40°C
V
= 5V
IN
+85°C
3
4
5
6
7
0
20
40
60
80
100
120
140
V
(V)
AMBIENT TEMPERATURE (°C)
FIGURE 14. INPUT QUIESCENT CURRENT vs TEMPERATURE
IN
FIGURE 15. INPUT QUIESCENT CURRENT vs INPUT VOLTAGE,
SHUTDOWN
FN8692 Rev.1.00
Mar 29, 2017
Page 8 of 18
ISL78692
Typical Operating Performance The test conditions for the Typical Operating Performance are: V = 5V,
IN
T
= +25°C, R
= 160kΩ, V = 3.7V, Unless Otherwise Noted. (Continued)
BAT
A
IREF
100
95
90
85
80
75
70
65
60
500
450
400
350
300
250
200
150
100
50
+70°C
+75°C
+85°C
+70°C
+85°C
+75°C
0
2.2
2.7
3.2
3.7
4.2
2.2
2.7
3.2
3.7
4.2
V
(V)
V
(V)
BAT
BAT
FIGURE 17. JUNCTION TEMPERATURE vs V
vs AMBIENT
FIGURE 16. V
vs I
vs AMBIENT TEMPERATURE,
BAT
= 200k, V = 5.5V,
BAT
BAT
= 200k, V = 5.5V, AIR FLOW = 0 LFM,
TEMPERATURE, R
R
IREF
IN
IREF
IN
AIR FLOW = 0 LFM, MEASURED ON THE
ISL78692EVAL1Z BOARD
MEASURED ON THE ISL78692EVAL1Z BOARD
When the input supply is not present, the ISL78692 draws less
than 1µA current from the battery.
Theory of Operation
The ISL78692 is an integrated charger for single-cell Lithium
chemistry batteries. The ISL78692 functions as a traditional
linear charger when powered with a voltage source adapter.
When powered with a current-limited adapter, the charger
minimizes the thermal dissipation commonly seen in traditional
linear chargers.
Three indication pins are available from the charger to indicate
the charge status. The V2P8 outputs a 2.8VDC voltage when the
input voltage is above the power-on reset (POR) level and can be
used as the power-present indication. This pin is capable of
sourcing a 2mA current, so it can also be used to bias external
circuits. The STATUS pin is an open-drain logic output that turns
LOW at the beginning of a charge cycle until the end-of-charge
(EOC) condition is qualified. The EOC condition is when the
battery voltage rises above the recharge threshold and the
charge current falls below a preset of a tenth of the programmed
charge current. Once the EOC condition is qualified, the STATUS
output rises to HIGH and is latched. The latch is released at the
beginning of a charge or recharge cycle. The open-drain FAULT
pin turns low when any fault conditions occur. The fault
conditions include the external battery temperature fault, a
charge time fault, or the battery removal.
As a linear charger, the ISL78692 charges a battery in the popular
constant current (CC) and constant voltage (CV) profile. The
constant charge current I
is programmable up to 1A with an
REF
external resistor or a logic input. The charge voltage V has 1%
CH
accuracy over the entire recommended operating condition range.
The charger preconditions the battery with a 10% typical of the
programmed current at the beginning of a charge cycle until the
battery voltage is verified to be above the minimum fast charge
voltage, V
. This low current preconditioning charge mode is
TRICKLE
named trickle mode. The verification takes 15 cycles of an internal
oscillator whose period is programmable with a timing capacitor
on the time pin. A thermal-foldback feature protects the device
from the thermal concern typically seen in linear chargers. The
charger reduces the charge current automatically as the IC
internal temperature rises above +100°C to prevent further
temperature rise. The thermal-foldback feature guarantees safe
operation when the printed circuit board (PCB) is space limited for
thermal dissipation.
Figure 18 shows the typical charge curves in a traditional linear
charger powered with a constant voltage adapter. From top to
bottom, the curves represent the constant input voltage, the
battery voltage, the charge current and the power dissipation in
the charger. The power dissipation P is given by Equation 1:
CH
(EQ. 1)
P
= V -V
I
CH
IN BAT CHARGE
where I
is the charge current. The maximum power
CHARGE
A TEMP pin monitors the battery temperature to ensure a safe
charging temperature range. The temperature range is
programmable with an external negative temperature coefficient
(NTC) thermistor. The TEMP pin is also used to detect the removal
of the battery.
dissipation occurs during the beginning of the CC mode. The
maximum power the IC is capable of dissipating is dependent on
the thermal impedance of the printed circuit board (PCB).
Figure 18 shows (with dotted lines) two cases that the charge
currents are limited by the maximum power dissipation
capability due to the thermal foldback.
The charger offers a safety timer for setting the fast charge time
(TIMEOUT) limit to prevent charging a dead battery for an extensively
long time. The trickle mode is limited to 1/8 of TIMEOUT.
The charger automatically recharges the battery when the
battery voltage drops below a recharge threshold of 3.9V (typ).
FN8692 Rev.1.00
Mar 29, 2017
Page 9 of 18
ISL78692
I . In the CC mode, the current loop tries to increase the charge
R
TRICKLE
MODE
CONSTANT CURRENT
MODE
CONSTANT VOLTAGE
MODE
INHIBIT
current by enhancing the sense MOSFET (Q
, which the
SEN)
sensed current matches the reference current. On the other
hand, the adapter current is limited, the actual output current will
never meet what is required by the current reference. As a result,
VIN
INPUT VOLTAGE
VCH
BATTERY VOLTAGE
the current error amplifier CA, keeps enhancing the Q
as well
SEN
VTRICKLE
as the main MOSFET Q
MAIN
until they are fully turned on.
Therefore, the main MOSFET becomes a power switch instead of
a linear regulation device. The power dissipation in the CC mode
ICHARGE
becomes Equation 2:
2
P
= r
I
DSON CHARGE
CH
CHARGE CURRENT
(EQ. 2)
ICHARGE/10
P1
where r
is the resistance when the main MOSFET is fully
DS(ON)
turned on. This power is typically much less than the peak power
in the traditional linear mode.
P2
P3
POWER DISSIPATION
The worst power dissipation when using a current-limited adapter
typically occurs at the beginning of the CV mode, as shown in
Figure 19.
TIMEOUT
FIGURE 18. TYPICAL CHARGE CURVES USING A CONSTANT VOLTAGE
ADAPTER
Equation 1 applies during the CV mode. When using a very small
PCB whose thermal impedance is relatively large, it is possible
that the internal temperature can still reach the thermal
foldback threshold. In that case, the IC is thermally protected by
lowering the charge current, as shown with the dotted lines in the
charge current and power curves. Appropriate design of the
adapter can further reduce the peak power dissipation of the
ISL78692. See “Applications Information” for more information.
TRICKLE
MODE
CONSTANT CURRENT
MODE
CONSTANT VOLTAGE
MODE
INHIBIT
INPUT VOLTAGE
VIN
VCH
BATTERY VOLTAGE
VTRICKLE
Figure 20 illustrates the typical signal waveforms for the linear
charger from the power-up to a recharge cycle. More detailed
information is given in the following.
ICHARGE
ILIM
Applications Information
CHARGE CURRENT
Power on Reset (POR)
ICHARGE/10
The ISL78692 resets itself as the input voltage rises above the
POR rising threshold. The V2P8 pin outputs a 2.8V voltage, the
internal oscillator starts to oscillate, the internal timer is reset,
and the charger begins to charge the battery. The two indication
pins, STATUS and FAULT, indicate a LOW and a HIGH logic signal
respectively. Figure 20 illustrates the start-up of the charger
P1
P2
POWER DISSIPATION
TIMEOUT
between t to t .
0
2
FIGURE 19. TYPICAL CHARGE CURVES USING A CURRENT-LIMITED
ADAPTER
The ISL78692 has a typical rising POR threshold of 3.4V and a
falling POR threshold of 2.4V. The 2.4V falling threshold
guarantees charger operation with a current-limited adapter to
minimize the thermal dissipation.
When using a current-limited adapter, the thermal situation in
the ISL78692 is totally different. Figures 19 shows the typical
charge curves when a current-limited adapter is employed. The
operation requires the I
to be programmed higher than the
Charge Cycle
A charge cycle consists of three charge modes: trickle mode,
constant current (CC) mode and constant voltage (CV) mode. The
charge cycle always starts with the trickle mode until the battery
REF
of the adapter. The key difference of the
limited current I
LIM
charger operating under such conditions occurs during the CC
mode.
voltage stays above V
(2.8V typical) for 15 consecutive
The “Block Diagram” on page 2 aids in understanding the
operation. The current loop consists of the current amplifier CA
TRICKLE
cycles of the internal oscillator. If the battery voltage drops below
during the 15 cycles, the 15-cycle counter is reset and
V
and the sense MOSFET (Q
. The current reference I is
TRICKLE
SEN)
R
the charger stays in the trickle mode. The charger moves to the CC
mode after verifying the battery voltage. As the battery pack
terminal voltage rises to the final charge voltage V , the CV mode
begins. The terminal voltage is regulated at the constant V in the
CH
CV mode and the charge current starts to reduce towards zero.
programmed by the IREF pin. The current amplifier CA regulates
the gate of the sense MOSFET (Q that the sensed current
SEN)
matches the reference current I . The main MOSFET Q
I
CH
SEN
and the sense MOSFET (Q
R
MAIN
form a current mirror with a ratio
SEN)
of 100,000:1, which the output charge current is 100,000 times
FN8692 Rev.1.00
Mar 29, 2017
Page 10 of 18
ISL78692
After the charge current drops below I
programmed to 1/10
A 1nF capacitor results in a 0.2ms oscillation period. The
accuracy of the period is mainly dependent on the accuracy of
the capacitance and the internal current source.
(EOC)
of I ; see “End-of-Charge (EOC) Current” on page 12 for more
REF
detail), the ISL78692 indicates the end-of-charge (EOC) with the
STATUS pin. The charging actually does not terminate until the
internal timer completes its length of TIMEOUT in order to bring the
battery to its full capacity. Signals in a charge cycle are illustrated
Total Charge Time
The total charge time for the CC mode and CV mode is limited to
a length of TIMEOUT. A 22-stage binary counter increments each
oscillation period of the internal oscillator to set the TIMEOUT.
The TIMEOUT can be calculated in Equation 4:
in Figure 20 between points t to t .
2
5
VIN
t
C
TIME
1nF
POR THRESHOLD
CHARGE CYCLE
22
OSCSEC
(EQ. 4)
-----------------------------
-----------------
minutes
TIMEOUT = 2
= 14
60
V2P8
CHARGE CYCLE
A 1nF capacitor leads to 14 minutes of TIMEOUT. For example, a
15nF capacitor sets the TIMEOUT to be 3.5 hours. The charger
has to reach the end-of-charge condition before the TIMEOUT,
otherwise, a TIMEOUT fault is issued. The TIMEOUT fault latches
up the charge and the FAULT pin goes low. There are two ways to
release such a latch-up either to recycle the input power, or
toggle the EN pin to disable the charger and then enable it again.
STATUS
FAULT
VBAT
15 CYCLES TO
1/8 TIMEOUT
VCH
The trickle charge mode has a time limit of 1/8 TIMEOUT. If the
VRECHRG
15 CYCLES
VTRICKLE
battery voltage does not reach V
within this limit, a
TRICKLE
TIMEOUT fault is issued and the charger latches off. The charger
stays in trickle mode for at least 15 cycles of the internal
oscillator and, at most, 1/8 of TIMEOUT, as shown in Figure 20.
IEOC
ICHARGE
T
T
T
T
T
T
4
T
T
T
8
0
1
2
3
5
6
7
Charge Current Programming
The charge current is programmed by the IREF pin. There are
three ways to program the charge current:
FIGURE 20. OPERATION WAVEFORMS
The following events initiate a new charge cycle:
• POR
1. Driving the IREF pin above 1.2V
2. Driving the IREF pin below 0.4V,
• A new battery being inserted (detected by TEMP pin)
3. Or using the R
page 1.
as shown in “TYPICAL APPLICATION” on
IREF
• The battery voltage drops below a recharge threshold after
completing a charge cycle
The voltage of IREF is regulated to a 0.8V reference voltage when
not driven by any external source. The charging current during the
constant current mode is 100,000 times that of the current in
• Recovery from an battery over-temperature fault
• Or, the EN pin is toggled from GND to floating
the R
resistor. Hence, depending on how IREF pin is used, the
IREF
charge current is given by Equation 5:
• Further description of these events are given later in this
datasheet
V
R
V
1.2V
IREF
IREF
IREF
500mA
0.8V
Recharge
5
(EQ. 5)
-----------------
I
=
10 A
REF
R
After a charge cycle completes, charging is prohibited until the
IREF
battery voltage drops to a recharge threshold, V
of 3.9V
80mA
RECHRG
0.4V
(TYP), (see “Electrical Specifications” on page 5”). Then a new
charge cycle starts at point t and ends at point t , as shown in
The internal reference voltage at the IREF pin is capable of sourcing
less than 100µA current. When pulling down the IREF pin with a
logic circuit, the logic circuit must be able to sink at least 100µA
current. For design purposes, a designer should assume a tolerance
of ±20% when computing the minimum and maximum charge
current from Equation 5.
6
8
Figure 20. The safety timer is reset at t .
6
Internal Oscillator
The internal oscillator establishes a timing reference. The
oscillation period is programmable with an external timing
capacitor, C
, as shown in Figure 1. The oscillator charges the
timing capacitor to 1.5V and then discharges it to 0.5V in one
TIME
When the adapter is current limited, it is recommended that the
reference current be programmed to at least 30% higher than the
adapter current limit (which equals the charge current). In addition,
the charge current should be at least 350mA, which the voltage
difference between the VIN and the VBAT pins is higher than 100mV.
The 100mV is the offset voltage of the input/output voltage
comparator shown in “Block Diagram” on page 2.
period, both with 10µA current. The period t
Equation 3:
is given by
OSC
6
t
= 0.2 10 C
seconds
OSC
TIME
(EQ. 3)
FN8692 Rev.1.00
Mar 29, 2017
Page 11 of 18
ISL78692
End-of-Charge (EOC) Current
NTC Thermistor
The end-of-charge current I
sets the level at which the charger
The ISL78692 uses two comparators (CP2 and CP3) to form a
window comparator, as shown in Figure 23. When the TEMP pin
EOC
starts to indicate the end of the charge with the STATUS pin, as
shown in Figure 20. The charger actually does not terminate
charging until the end of the TIMEOUT, as described in “Total
voltage is “out of the window,” determined by the V
and
TMIN
, the ISL78692 stops charging and indicates a fault
V
TMAX
Charge Time” on page 11. The I
is set to 60mA (typ) internal
node to V2P8.
condition. When the temperature returns to the set range, the
charger re-starts a charge cycle. The two MOSFETs, Q1 and Q2,
produce hysteresis for both upper and lower thresholds. The
temperature window is shown in Figure 22.
EOC
to the device by tying the I
EOC
Charge Current Thermal Foldback
Overheating is always a concern in a linear charger. The
maximum power dissipation usually occurs at the beginning of a
charge cycle when the battery voltage is at its minimum but the
charge current is at its maximum. The charge current thermal
foldback function in the ISL78692 frees users from the
overheating concern.
2.8V
V
TMIN (1.4V)
VTMIN- (1.2V)
TEMP
PIN
Figure 21 shows the current signals at the summing node of the
current error amplifier in “Block Diagram” on page 2. I is the
VOLTAGE
R
reference and I is the current from the temperature monitoring
T
block. The I has no impact on the charge current until the
internal temperature reaches approximately +100°C (+85°C
T
V
TMAX+ (0.406V)
VTMAX (0.35V)
Min) then I rises at a rate of 1µA/°C. When I rises, the current
T
T
0V
control loop forces the sensed current I
to reduce at the same
SEN
rate. As a mirrored current, the charge current is 100,000 times
that of the sensed current and reduces at a rate of 100mA/°C.
For a charger with the constant charge current set at 1A, the
charge current is reduced to zero when the internal temperature
rises to +110°C. The actual charge current settles between
+100°C to +110°C.
UNDER-
TEMPERATURE
OVER-
TEMPERATURE
FIGURE 22. CRITICAL VOLTAGE LEVELS FOR TEMP PIN
The charge current should not drop below I
EOC
because of the
2.8V
thermal foldback. For some extreme cases (if that does happen)
the charger does not indicate end-of-charge unless the battery
voltage is already above the recharge threshold.
V2P8
ISL78692
R1
40K
VRMV
BATTERY
REMOVAL
CP1
CP2
-
+
RU
R2
60K
IR
VTMIN
UNDER-
TEMPERATURE
-
R3
TO TEMP PIN
+
75K
TEMP
IT
Q1
OVER-
TEMPERATURE
CP3
R4
-
25K
RT
ISEN
VTMAX
+
Q2
R5
4K
GND
+100°C
TEMPERATURE
FIGURE 21. CURRENT SIGNALS AT THE AMPLIFIER AC INPUT
FIGURE 23. THE INTERNAL AND EXTERNAL CIRCUIT FOR THE NTC
INTERFACE
2.8V Bias Voltage
The ISL78692 provides a 2.8V voltage for biasing the internal
control and logic circuit. This voltage is also available for external
circuits such as the NTC thermistor circuit. The maximum
allowed external load is 2mA.
As the TEMP pin voltage rises from low and exceeds the 1.4V
threshold, the under-temperature signal rises and does not clear
until the TEMP pin voltage falls below the 1.2V falling threshold.
Similarly, the over-temperature signal is given when the TEMP pin
voltage falls below the 0.35V threshold and does not clear until the
voltage rises above 0.406V. The actual accuracy of the 2.8V is not
important because all the thresholds and the TEMP pin voltage are
ratios determined by the resistor dividers, as shown in Figure 23.
FN8692 Rev.1.00
Mar 29, 2017
Page 12 of 18
ISL78692
The NTC thermistor is required to have a resistance ratio of 7:1 at
the low and the high temperature limits, that is given by
Equation 6:
to connect the TEMP pin to the IREF pin that has a 0.8V output.
With such connection, the IREF pin can no longer be
programmed with logic inputs. In this condition no pull-up is
allowed for the TEMP pin.
R
COLD
-------------------
= 7
(EQ. 6)
R
HOT
Battery Removal Detection
The ISL78692 assumes that the thermistor is co-packed with the
battery and is removed together with the battery. When the
charger senses a TEMP pin voltage that is 2.1V or higher, it
assumes that the battery is removed. The battery removal
detection circuit is also shown in Figure 23. When a battery is
removed, a FAULT signal is indicated and charging is halted.
When a battery is inserted again, a new charge cycle starts.
This is because at the low temperature limit, the TEMP pin
voltage is 1.4V, which is 1/2 of the 2.8V bias, as shown in
Equation 7:
R
= R
U
(EQ. 7)
COLD
where R is the pull-up resistor as shown in Figure 23. On the
U
other hand, at the high temperature limit the TEMP pin voltage is
0.35V, 1/8 of the 2.8V bias (see Equation 8):
Indications
R
U
7
The ISL78692 has three indications: the input presence, the
charge status, and the fault indication. The input presence is
indicated by the V2P8 pin while the other two indications are
presented by the STATUS pin and FAULT pin respectively.
Figure 24 shows the V2P8 pin voltage vs the input voltage.
Table 3 summarizes the other two pins.
(EQ. 8)
-------
=
R
HOT
Various NTC thermistors are available for this application. Table 2
shows the resistance ratio and the negative temperature
coefficient of the curve-1 NTC thermistor from Vishay at various
temperatures. The resistance at +3°C is approximately seven
times the resistance at +47°C, which is shown in Equation 9:
R
3C
(EQ. 9)
----------------
= 7
3.4V
R
47C
2.4V
If the low temperature limit is +3°C, and the high temperature
limit is around +47°C. The pull-up resistor RU can be chosen to be
the resistance measured at +3°C.
2.8V
VIN
TABLE 2. RESISTANCE RATIO OF VISHAY’S CURVE-1 NTC
TEMPERATURE (°C)
R /R
NTC (%/°C)
5.1
T
25°C
0
3
3.266
V2P8
2.806
2.540
5.1
5
5.0
25
45
47
50
1.000
4.4
FIGURE 24. THE V2P8 PIN OUTPUT vs THE INPUT VOLTAGE AT THE
VIN PIN. VERTICAL: 1V/DIV, HORIZONTAL:
100ms/DIV
0.4368
0.4041
0.3602
4.0
3.9
TABLE 3. STATUS INDICATIONS
3.9
FAULT
High
STATUS
High
INDICATION
Charge completed with no fault (Inhibit) or Standby
Charging in one of the three modes
Fault
The temperature hysteresis will now be estimated in the low and
high temperatures. At the low temperature, the hysteresis is
approximately estimated in Equation 10:
High
Low
Low
1.4V-1.2V
1.4V 0.051
High
-------------------------------
T
3
C
hysLOW
(EQ. 10)
*Both outputs are pulled up with external resistors.
where 0.051 is the NTC at +3°C. Similarly, the high temperature
hysteresis is estimated in Equation 11:
Shutdown
The ISL78692 can be shut down by pulling the EN pin to ground.
When shut down, the charger draws typically less than 30µA
current from the input power and the 2.8V output at the V2P8 pin
is also turned off. The EN pin has to be driven with an open-drain
or open-collector logic output. The EN pin is internally biased, so
the pin should be floated to turn the device ON once the charger
is enabled. To turn OFF the device an open drain/open collector
can be used to pull the pin to its low level.
0.406V-0.35V
0.35V 0.039
-------------------------------------
T
4
C
hysHIGH
(EQ. 11)
where the 0.039 is the NTC at +47°C.
For applications that do not need to monitor the battery
temperature, the NTC thermistor can be replaced with a regular
resistor of a half value of the pull-up resistor R . Another option is
U
FN8692 Rev.1.00
Mar 29, 2017
Page 13 of 18
ISL78692
Input and Output Capacitor Selection
C
VNL
RO
=
(VNL - VFL )/ILIM
The use of a 10µF Tantalum type TCA106M016R0200 or
Ceramic type C3216X7RC1106KT000N or equivalent is
recommended for the input. When used as a charger, the output
capacitor should be 2x10µF Tantalum type AVX
VFL
B
VPACK
RO
RPACK
TCJA106M016R0200 or equivalent. The device partially relies on
the ESR (equivalent series resistance) of the output capacitor for
the loop stability. If there is a need to use ceramic capacitors for
device output, it is recommended to use a 220mΩ, 0.25W
resistor, in series with the VBAT pin followed by 2x10µF, 16V, X7R
ceramic capacitor C3216X7RC1106KT000N or equivalent for an
ILIM
VNL
VCELL
A
ILIM
I
= 0.5A (see Figure 25).
FIGURE 26. THE IDEAL I-V CHARACTERISTICS OF A CURRENT
LIMITED POWER SUPPLY
BAT
ISL78692
220m, 0.25W
Working with Current-Limited Power Supply
TO INPUT
TO BATTERY
VIN
VBAT
As described earlier, the ISL78692 minimizes the thermal
dissipation when running off a current-limited AC adapter, as
shown in Figure 19. The thermal dissipation can be further
reduced when the adapter is properly designed. The following
demonstrates that the thermal dissipation can be minimized if
the adapter output reaches the full-load output voltage (point B
in Figure 26) before the battery pack voltage reaches the final
charge voltage (4.1V). The assumptions for the following
discussion are: the adapter current limit = 500mA, the battery
pack equivalent resistance = 200mΩ, and the charger
ON-resistance is 350mΩ.
R1
C1
10µF
Ceramic
C2
LARGE
CERAMIC
CAPACITOR
GND
FIGURE 25. INSERTING R TO IMPROVE THE STABILITY OF
1
APPLICATIONS WITH LARGE CERAMIC CAPACITOR
USED AT THE OUTPUT
Current-Limited Adapter
When charging in the constant current region, the pass element
in the charger is fully turned on. The charger is equivalent to the
ON-resistance of the internal P-Channel MOSFET. The entire
charging system is equivalent to the circuit shown in Figure 27A.
Figure 26 shows the ideal current voltage characteristics of a
current-limited adapter. The V is the no-load adapter output
NL
voltage and V is the full load voltage at the current limit I
.
FL LIM
Before its output current reaches the limit I , the adapter
LIM
presents the characteristics of a voltage source. The slope, r ,
represents the output resistance of the voltage supply. For a well
regulated supply, the output resistance can be very small, but
some adapters naturally have a certain amount of output
resistance.
The charge current is the constant current limit I , and the
LIM
O
adapter output voltage can be easily found out as calculated in
Equation 12:
(EQ. 12)
V
= I
r V
DSON PACK
Adapter
LIM
where V
is the battery pack voltage. The power dissipation in
The adapter is equivalent to a current source when running in the
constant current region. Being a current source, its output
voltage is dependent on the load, which in this case, is the
charger and the battery. As the battery is being charged, the
adapter output rises from a lower voltage in the current voltage
characteristics curve, such as point A, to higher voltage until
reaching the breaking point B, as shown in Figure 26.
PACK
the charger is given in Equation 2, where I
= I .
CHARGE LIM
A critical condition of the adapter design is that the adapter
output reaches point B in Figure 26 at the same time as the
battery pack voltage reaches the final charge voltage (4.1V), that
is given by Equation 13:
V
= I
rDSON + V
CH
(EQ. 13)
Critical
LIM
The adapter is equivalent to a voltage source with output
resistance when running in the constant voltage region; because
of this characteristic. As the charge current drops, the adapter
output moves from point B to point C, shown in Figure 26.
For example, if the final charge voltage is 4.1V, the r
350mΩ, and the current limit I
full-load voltage is 4.275V.
is
is 500mA, the critical adapter
DS(ON)
LIM
The battery pack can be approximated as an ideal cell with a
lumped-sum resistance in series, also shown in Figure 26. The
ISL78692 charger sits between the adapter and the battery.
When the above condition is true, the charger enters the
constant voltage mode simultaneously as the adapter exits the
current limit mode. The equivalent charging system is shown in
Figure 27C. Since the charge current drops at a higher rate in the
constant voltage mode than the increase rate of the adapter
voltage, the power dissipation decreases as the charge current
decreases. Therefore, the worst case thermal dissipation occurs
in the constant current charge mode. Figure 27A shows the I-V
curves of the adapter output, the battery pack voltage and the
cell voltage during the charge. The 5.9V no-load voltage is just an
example value higher than the full-load voltage. The cell voltage
FN8692 Rev.1.00
Mar 29, 2017
Page 14 of 18
ISL78692
4.05V uses the assumption that the pack resistance is 200mΩ.
Figure 28A illustrates the adapter voltage, battery pack voltage,
the charge current and the power dissipation in the charger
respectively in the time domain.
fully charge the battery as long as the no-load voltage is above
4.1V. Figure 28B illustrates the adapter voltage, battery pack
voltage, the charge current and the power dissipation in the
charger respectively in the time domain.
If the battery pack voltage reaches 4.1V before the adapter
reaches point B in Figure 26, a voltage step is expected at the
adapter output when the pack voltage reaches the final charge
voltage. As a result, the charger power dissipation is also
expected to have a step rise. This case is shown in Figure 19 as
well as Figure 29C. Under this condition, the worst case thermal
dissipation in the charger happens when the charger enters the
constant voltage mode.
Based on the previous discussion, the worst-case power
dissipation occurs during the constant current charge mode if the
adapter full-load voltage is lower than the critical voltage given in
Equation 13. Even if that is not true, the power dissipation is still
much less than the power dissipation in the traditional linear
charger. Figures 26 and 27 are scope-captured waveforms to
demonstrate the operation with a current-limited adapter.
The waveforms in Figure 26 are the adapter output voltage
(1V/div), the battery voltage (1V/div), and the charge current
(200mA/div) respectively. The time scale is 1ks/div. The adapter
current is limited to 600mA and the charge current is
programmed to 1A. Note that the voltage difference is only
approximately 200mV and the adapter voltage tracks the battery
voltage in the CC mode. Figure 26 also shows the resistance limit
mode before entering the CV mode.
If the adapter voltage reaches the full-load voltage before the
pack voltage reaches 4.1V, the charger will experience the
resistance-limit situation. In this situation, the ON-resistance of
the charger is in series with the adapter output resistance. The
equivalent circuit for the resistance-limit region is shown in
Figure 27B. Eventually, the battery pack voltage will reach 4.1V
because the adapter no-load voltage is higher than 4.1V, then
Figure 27C becomes the equivalent circuit until charging ends. In
this case, the worst-case thermal dissipation also occurs in the
constant current charge mode. Figure 28B shows the I-V curves of
the adapter output, the battery pack voltage and the cell voltage
for the case VFL = 4V. In the case, the full-load voltage is lower
than the final charge voltage (4.1V), but the charger is still able to
Figure 27 shows the actual captured waveforms depicted in
Figure 29C. The constant charge current is 750mA. A step in the
adapter voltage during the transition from CC mode to CV mode
is demonstrated.
ADAPTER
RO
ADAPTER
CHARGER
rDS(ON)
ADAPTER
RO
CHARGER
CHARGER
rDS(ON)
VPACK
4.1V DC
OUTPUT
VADAPTER
VPACK
VPACK
VADAPTER
VADAPTER
VNL
ILIM
VNL
I
I
I
RPACK
RPACK
RPACK
BATTERY
PACK
BATTERY
PACK
VCELL
VCELL
BATTERY
PACK
VCELL
FIGURE 27A. THE EQUIVALENT CIRCUIT IN THE FIGURE 27B. THE EQUIVALENT CIRCUIT IN THE FIGURE 27C. THE EQUIVALENT CIRCUIT WHEN
CONSTANT CURRENT REGION
RESISTANCE-LIMIT REGION
THE PACK VOLTAGE REACHES
THE FINAL CHARGE VOLTAGE
FIGURE 27. THE EQUIVALENT CIRCUIT OF THE CHARGING SYSTEM WORKING WITH CURRENT LIMITED ADAPTERS
VPACK
5.9V
4.1V
VNL
VADAPTER
VADAPTER
4.1V
4.0V
4.1V
4.275V
4.1V
VPACK
VCELL
VCELL
3.775V
3.625V
3.9V
500mA
500mA
FIGURE 28A.
FIGURE 28B.
FIGURE 28. THE I-V CHARACTERISTICS OF THE CHARGER WITH DIFFERENT CURRENT LIMITED POWER SUPPLIES
FN8692 Rev.1.00
Mar 29, 2017
Page 15 of 18
ISL78692
VIN
VIN
VIN
VPACK
VPACK
VPACK
CHARGE
CURRENT
CHARGE
CURRENT
CHARGE
CURRENT
POWER
POWER
POWER
TIME
TIME
TIME
CONSTANT
CURRENT
CONSTANT
CURRENT
RES
LIMIT
CONSTANT
VOLTAGE
CONSTANT
VOLTAGE
CONSTANT CURRENT
CONSTANT VOLTAGE
FIGURE 29A.
FIGURE 29B.
FIGURE 29C.
FIGURE 29. THE OPERATING CURVES WITH THREE DIFFERENT CURRENT LIMITED POWER SUPPLIES
IREF Programming Using Current-Limited
Adapter
V
IN
The ISL78692 has 20% tolerance for the charge current.
Typically, the current-limited adapter also has 10% tolerance. In
order to guarantee proper operation, it is recommended that the
nominal charge current be programmed at least 30% higher
than the nominal current limit of the adapter.
V
BAT
Board Layout Recommendations
The ISL78692 internal thermal foldback function limits the
charge current when the internal temperature reaches
approximately +100°C. In order to maximize the current
capability, it is very important that the exposed pad under the
package is properly soldered to the board and is connected to
other layers through thermal vias. More thermal vias and more
copper attached to the exposed pad usually result in better
thermal performance. On the other hand, the number of vias is
limited by the size of the pad. The 3x3 DFN package allows 9 vias
be placed in three rows. Since the pins on the 3x3 DFN package
are on only two sides, as much top layer copper as possible
should be connected to the exposed pad to minimize the thermal
impedance. Refer to UG001, “ISL78692EVAL1Z Evaluation Board
User Guide”for layout example.
I
BAT
1 hour
FIGURE 31. SCOPE WAVEFORMS SHOWING THE CASE THAT THE
FULL-LOAD POWER SUPPLY VOLTAGE IS HIGHER THAN
THE CRITICAL VOLTAGE
V
IN
V
BAT
CV Mode
I
BAT
CC Mode
Resistance Limit Mode
FIGURE 30. SCOPE WAVEFORMS SHOWING THE THREE MODE
FN8692 Rev.1.00
Mar 29, 2017
Page 16 of 18
ISL78692
Revision History The revision history provided is for informational purposes only and is believed to be accurate, but not warranted.
Please visit our website to make sure you have the latest revision.
DATE
REVISION
FN8692.1
CHANGE
March 29, 2017
Added Key Differences Between Family of parts on page 2.
Ordering Information table on page 4: added to Note 1, -T7A and tape and reel quantities.
Updated POD L10.3x3 on page 18 from rev 10 to rev 11. Changes since rev 10:
Tiebar Note 4 updated
From: Tiebar shown (if present) is a non-functional feature.
To: Tiebar shown (if present) is a non-functional feature and may be located on any of the 4 sides (or ends).
September 10, 2014
FN8692.0
Initial Release.
About Intersil
Intersil Corporation is a leading provider of innovative power management and precision analog solutions. The company's products
address some of the largest markets within the industrial and infrastructure, mobile computing and high-end consumer markets.
For the most updated datasheet, application notes, related documentation and related parts, please see the respective product
information page found at www.intersil.com.
For a listing of definitions and abbreviations of common terms used in our documents, visit: www.intersil.com/glossary.
You may report errors or suggestions for improving this datasheet by visiting www.intersil.com/ask.
Reliability reports are also available from our website at www.intersil.com/support
© Copyright Intersil Americas LLC 2014-2017. All Rights Reserved.
All trademarks and registered trademarks are the property of their respective owners.
For additional products, see www.intersil.com/en/products.html
Intersil Automotive Qualified products are manufactured, assembled and tested utilizing TS16949 quality systems as noted
in the quality certifications found at www.intersil.com/en/support/qualandreliability.html
Intersil products are sold by description only. Intersil may modify the circuit design and/or specifications of products at any time without notice, provided that such
modification does not, in Intersil's sole judgment, affect the form, fit or function of the product. Accordingly, the reader is cautioned to verify that datasheets are
current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its
subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com
FN8692 Rev.1.00
Mar 29, 2017
Page 17 of 18
ISL78692
For the most recent package outline drawing, see L10.3x3.
Package Outline Drawing
L10.3x3
10 LEAD DUAL FLAT PACKAGE (DFN)
Rev 11, 3/15
5
3.00
A
B
PIN #1 INDEX AREA
1
2
5
PIN 1
INDEX AREA
10 x 0.23
(4X)
0.10
1.60
10x 0.35
TOP VIEW
BOTTOM VIEW
A B
C
M
0.10
(4X)
0.415
0.23
0.35
SEE DETAIL "X"
0.10
(10 x 0.55)
(10x 0.23)
C
C
BASE PLANE
0.20
SEATING PLANE
0.08 C
SIDE VIEW
(8x 0.50)
0.415
4
0.20 REF
0.05
C
1.60
2.85 TYP
DETAIL "X"
TYPICAL RECOMMENDED LAND PATTERN
NOTES:
1. Dimensions are in millimeters.
Dimensions in ( ) for Reference Only.
2. Dimensioning and tolerancing conform to ASME Y14.5m-1994.
3. Unless otherwise specified, tolerance : Decimal ± 0.05
4. Tiebar shown (if present) is a non-functional feature and may be
located on any of the 4 sides (or ends).
5. The configuration of the pin #1 identifier is optional, but must be
located within the zone indicated. The pin #1 identifier may be
either a mold or mark feature.
FN8692 Rev.1.00
Mar 29, 2017
Page 18 of 18
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